[zucchini] Use deque to store rel32_locations.

An optimization to reduce zucchini peak memory footprint.
MakeReadRel32 bring peak memory unnecessarily high due to std::vector
allocation heuristic, along with shrink_to_fit which temporarily
forces additional allocation: in the order of 32MB+19MB while only
19MB was needed.
deque puts less memory pressure than vector since it doesn't have
contiguous requirement and shrink_to_fit can be done in-place.

deque
Zucchini.PeakPagefileUsage 738876 KiB
Zucchini.PeakPagefileUsageChange 717436 KiB
Zucchini.PeakWorkingSetSize 632284 KiB
Zucchini.PeakWorkingSetSizeChange 623464 KiB
Zucchini.TotalTime 9.40955 s

vector
Zucchini.PeakPagefileUsage 755252 KiB
Zucchini.PeakPagefileUsageChange 733820 KiB
Zucchini.PeakWorkingSetSize 632660 KiB
Zucchini.PeakWorkingSetSizeChange 624616 KiB
Zucchini.TotalTime 10.3224 s

Bug: 1194281
Change-Id: Ic5a7f529d4465241990dbe27a485a67b32ab44b1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2830864
Commit-Queue: Etienne Pierre-Doray <etiennep@chromium.org>
Reviewed-by: Samuel Huang <huangs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#873383}
NOKEYCHECK=True
GitOrigin-RevId: 52f908bb699f8d106a1c43e10257759cce90500d

1 files changed, 3 insertions, 1 deletions

diff --git a/disassembler_elf.h b/disassembler_elf.h
index e279c29..60d524c 100644
--- a/disassembler_elf.h
+++ b/disassembler_elf.h
@@ -7,6 +7,7 @@
 
 #include <stdint.h>
 
+#include <deque>
 #include <memory>
 #include <string>
 #include <vector>
@@ -178,7 +179,8 @@ class DisassemblerElfIntel : public DisassemblerElf<Traits> {
 
  private:
   // Sorted file offsets of rel32 locations.
-  std::vector<offset_t> rel32_locations_;
+  // Using std::deque to reduce peak memory footprint.
+  std::deque<offset_t> rel32_locations_;
 
   DISALLOW_COPY_AND_ASSIGN(DisassemblerElfIntel);
 };